The present invention relates to an image reading apparatus for optically reading an image recorded on a document, on the basis of a detection signal of an image pickup device.
In an image reading apparatus such as a scanner, light is projected onto a document placed on an image reading window configured of a transparent member such as a glass plate, and then the light reflected from the document is converted into an electric signal by an image pickup device such as a CCD (Charge-Coupled Device) and a CIS (Contact Image Sensor), so that the image such as characters recorded on the document is read.
Methods of placing a document on an image reading window include: a method that a user (person) places a document directly on an image reading window; and a method that a document placed on a document placement section provided separately from an image reading window is fed to a document reading window automatically by an automatic document feeder.
In the method of automatic feeding to the document reading window, it need be detected whether all the documents placed on the document placement section are fed to the image reading section, that is, whether any document is present in the document placement section. Then, on the basis of this detection result, stop control need to be performed for the automatic document feeder.
For example, Japanese Patent Application Laid-Open No. H10-152230 describes that a plurality of swingable arm-shaped sensor actuators are provided such that the tip side of each sensor actuator contacts with a document placed on a document placement section. Then, on the basis of whether these sensor actuators contact with a document, it is detected whether any document is present in the document placement section.